1. Field of the Invention
The present invention relates to an automatic transmission control system for a vehicle for controlling a variety of operating devices in the automatic transmission of the vehicle, such as a creep-preventing device or a direct clutch, in accordance with the running state of the vehicle.
2. Description of the Prior Art
A creep-preventing device is used to release or damp the coupling force of the starting clutch so as to prevent the so-called "creep phenomenon" in which a vehicle is liable to run forward when the shift lever is set at its drive position with the engine idling. A direct clutch mechanically couples pump vane wheel and turbine vane wheel so as to eliminate any slippage in the clutch region of a fluid torque converter. The throttle valve opening of the engine plays an important role in the generation of control signals for both.
As a throttle valve-opening detector for detecting a predetermined opening of the throttle valve to generate an electric signal, there is known in the art a device in which a switch is disposed oppositely to an accelerator pedal arm for controlling the opening of the throttle valve so that the switch is operated at a predetermined opening of the throttle valve by the accelerator pedal arm. Since a plurality of predetermined openings of the throttle valve must be detected to control the creep-preventing device, the direct clutch and so on described hereinbefore, however, the device according to the prior art requires a number of switches that corresponds to the number of predetermined openings, thus raising a disadvantage that it is expensive to produce.